This invention relates in general to rocket engines and in particular to a new and useful method for forming an insulating layer between a propellant charge and the walls of the combustion chamber of the rocket engine which comprises applying an expandable plastic to the inside of the combustion chamber housing between the housing and the circumference of the propellant charge and then expanding the plastic.
A method relating to propellant charge insulation preparation is discosed in German patent application No. P 31 05 932.5. In this prior art method, the expandable material is introduced by pressure into an annular space between the propellant charge and the combustion chamber housing, and allowed to cure or set. To obtain a maximum diameter of the propellant charge, and thus a correspondingly large operating range of the missile, it is sought to minimize the thickness of the insulating layer, for example to a thickness of less than 3 mm. Such a narrow annular gap, however, can be filled only to a certain extent if this prior art method is applied. Further, a high pressure must be provided, which makes the produced foamed plastic non-homogeneous.